needs NOOP for the master.

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@9404 71c3de6d-444a-0410-be80-ed276b4c234a

core/src/main/java/hudson/model/Computer.java

@@ -287,7 +287,8 @@ public abstract class Computer extends AbstractModelObject {
      * {@link RetentionStrategy} associated with this computer.
      *
      * @return
-     *      never null.
+     *      never null. This method return {@code RetentionStrategy<? super T>} where
+     *      {@code T=this.getClass()}.
      */
     public abstract RetentionStrategy getRetentionStrategy();
 

core/src/main/java/hudson/model/Hudson.java

@@ -2357,7 +2357,7 @@ public final class Hudson extends View implements ItemGroup<TopLevelItem>, Node,
         }
 
         public RetentionStrategy getRetentionStrategy() {
-            return RetentionStrategy.Always.INSTANCE;
+            return RetentionStrategy.NOOP;
         }
 
         @Override

core/src/main/java/hudson/slaves/RetentionStrategy.java

@@ -34,6 +34,18 @@ public abstract class RetentionStrategy<T extends Computer> implements Describab
         Always.DESCRIPTOR
     );
 
+    /**
+     * Dummy instance that doesn't do any attempt to retention.
+     */
+    public static final RetentionStrategy<Computer> NOOP = new RetentionStrategy<Computer>() {
+        public long check(Computer c) {
+            return 1;
+        }
+
+        public Descriptor<RetentionStrategy<?>> getDescriptor() {
+            throw new UnsupportedOperationException();
+        }
+    };
     
     /**
      * {@link RetentionStrategy} that tries to keep the node online all the time.

core/src/main/java/hudson/slaves/SlaveAvailabilityStrategy.java

-package hudson.slaves;
-
-import hudson.ExtensionPoint;
-import hudson.model.Describable;
-import hudson.model.Descriptor;
-import hudson.model.Slave;
-import hudson.util.DescriptorList;
-import org.kohsuke.stapler.DataBoundConstructor;
-
-/**
- * Slave availability strategy
- */
-public abstract class SlaveAvailabilityStrategy implements Describable<SlaveAvailabilityStrategy>, ExtensionPoint {
-
-    /**
-     * This method will be called periodically to allow this strategy to decide what to do with it's owning slave.
-     * The default implementation takes the slave on-line every time it's off-line.
-     *
-     * @param slave The slave that owns this strategy, i.e. {@code slave.getAvailabilityStrategy() == this}
-     * @param state Some state information that may be useful in deciding what to do.
-     * @return The number of minutes after which the strategy would like to be checked again. The strategy may be
-     *         rechecked earlier or later that this!
-     */
-    public abstract long check(Slave slave, State state);
-
-    /**
-     * All registered {@link SlaveAvailabilityStrategy} implementations.
-     */
-    public static final DescriptorList<SlaveAvailabilityStrategy> LIST = new DescriptorList<SlaveAvailabilityStrategy>(
-            Always.DESCRIPTOR
-    );
-
-    public static final class State {
-        private final boolean jobWaiting;
-        private final boolean jobRunning;
-
-        public State(boolean jobWaiting, boolean jobRunning) {
-            this.jobWaiting = jobWaiting;
-            this.jobRunning = jobRunning;
-        }
-
-        public boolean isJobWaiting() {
-            return jobWaiting;
-        }
-
-        public boolean isJobRunning() {
-            return jobRunning;
-        }
-    }
-
-    /**
-     * {@link SlaveAvailabilityStrategy} that tries to keep the node online all the time.
-     */
-    public static class Always extends SlaveAvailabilityStrategy {
-        @DataBoundConstructor
-        public Always() {
-        }
-
-        public long check(Slave slave, State state) {
-            SlaveComputer c = slave.getComputer();
-            if (c != null && c.isOffline() && c.isLaunchSupported())
-                c.tryReconnect();
-            return 5;
-        }
-
-        public Descriptor<SlaveAvailabilityStrategy> getDescriptor() {
-            return DESCRIPTOR;
-        }
-
-        public static final DescriptorImpl DESCRIPTOR = new DescriptorImpl();
-
-        private static class DescriptorImpl extends Descriptor<SlaveAvailabilityStrategy> {
-            public DescriptorImpl() {
-                super(Always.class);
-            }
-
-            public String getDisplayName() {
-                return "Keep this slave on-line as much as possible";
-            }
-        }
-    }
-}